I don't really see any dissonance there. After resting a few nights, you trigger the night scene where everyone at the camp is suffering. You then just wake up the next day like nothing happened. At this point anyone (players and characters alike) should reach the logical conclusion that the transformation wont happen for an unknown reason considering you know how fast a transformation happen after the symptoms.
A couple issues here:
Your phrase "after resting a few nights" can be very late in Act 1. Until you get that cutscene, it's reasonable to assume that there are some consequences for resting. As it is easily possible to get to the Underdark+ with only a few long rests, some players might play through the majority of EA, rushing through and resting infrequently, before they realize this. They'd miss a huge amount of content.
Camp cutscenes can get overwritten by newer ones. In my first playthrough, my first rest was after reaching Nettie, and thus my first long rest cutscene was with Raphael. And afterwards, I never encountered the "feeling sick" camp cutscene. This phenomenon may or may not have been updated since.
My solution(s): the game should essentially force you to rest before reaching the Grove, to ensure players get that "feeling sick" camp cutscene early. E.g.,:
- After rescuing Lae'zel, or otherwise getting similarly close to the Grove, the game could give you a cutscene where you have to avoid an overwhemingly huge goblin patrol and thus the party finds a secluded camp to hunker down for the night.
- Or, BG3 could give characters levels of exhaustions, along with companions voicing their feelings of sickness, strongly encouraging players to rest. The most dedicated players could try to push through, but at least there would be a game-given sign that it's okay to rest.
